This invention relates to an apparatus and method of removing sediment, sand, gravel, fines, organic material, suspended material, debris, and/or particulates (generically referred to as sediment) from a waterway. It is also capable of removing colloids, heavy metals and contaminates that travel near the bottom of the flow. More particularly, this invention relates to a sediment removal system that can balance or tune a suction discharge from a collector with a return discharge to the collector. This balanced system reduces water intake requirements through a screen or prescreen as the water, and sediment carried by the water, proceed toward a collector cavity. The balanced system also reduces or eliminates impingement or capture of selected types of sediment, such as organic matter, during the pumping sequence. Thus, this system provides an assembly and a method of regulating removal of sediment from the waterway. The system can also be used in the reverse form to provide a flow of water out of the screen, which allows heavy particles or sediment to fall into the hopper through the flow, which cleans the particles or sediment of organics, or other materials.
U.S. Pat. No. 6,042,733 and patents claiming priority therefrom relate to a collector that provides a simple, economical structure effective in filtering and removing sediment from a waterway, such as a river, stream, creek, irrigation channel, tidal pool, estuary pool, ocean, etc. The details of the '733 patent are expressly incorporated herein by reference. The collector is typically installed on a bottom surface of the waterway. A leading or upstream end of the collector includes a sloping or tapering surface that compresses the water and sediment as it moves up the ramp. At least one opening is provided near an apex and/or trailing edge of the collector and the opening is typically covered by a screen or prescreen that determines the size of the sediment that can enter the collector opening. The opening interconnects and communicates with an interior cavity of the collector. As the velocity of the water carrying the sediment travels over the apex and trailing edge, the velocity of the water slows and heavier sediment settles from the flow and passes through the opening into the collector cavity.
A sediment removal passage or suction passage communicates with the cavity and periodically (or continuously) removes the collected sediment slurry from the collector. This sediment slurry is preferably removed to a filter that is typically mounted on the bank or shore of the waterway. A suction force, for example provided by a pump, directs the sediment slurry through the removal passage and directs the slurry to the filter where the water is separated from the sediment. Clean, filtered water is then returned to the waterway. The pump is typically operated on a periodic basis to remove the sediment gathered in the collector cavity, although it will be appreciated that in some systems it may be desirable to operate the pump continuously in order to remove sediment on a constant basis.
The collector is typically manufactured of a durable material such as metal or concrete. Of course, various materials of construction that are particularly suitable for the intended use and environment may be used without departing from the scope and intent of the invention.
As will be appreciated, when the sediment is pumped from the collector cavity, the suction force draws additional water and sediment from the waterway because the collector cavity communicates with the waterway through the opening. In certain applications, it is desirable to reduce or limit the amount of water intake that enters the collector during the pumping sequence. In other instances, it is desirable to regulate the type of material that is captured by the collector, i.e., to further control the type of sediment that is removed from the waterway. As is known from the '733 patent, the slope of the collector surfaces and the size of the openings and mesh size of the screens determine what type of materials are collected. In some instances, however, a flat collector (i.e., a collector without the sloped surfaces) may be desirable that still allows selectivity of the type of material removed from the waterway.
Therefore, a need exists to provide variability in the type or density of sediment collected, as well as providing for adjustable sediment removal with a flat collector.